Established by President Theodore Roosevelt in 1907, Gila Cliff Dwellings National Monument protects and interprets a complex of 15th-century Mogollon cliff dwellings and other associated prehistoric sites, and the diverse natural environment that attracted and supported these early civilizations. The location of these important prehistoric resources is directly related to scarce and important natural resources: the perennial waters and associated rich natural resources of the upper Gila River. The primary natural resource issues of concern at the park include invasive exotic plants and aquatic invasive species, such as American bullfrog (Lithobates catesbeiana) and crayfish (Orcontectes spp.), and the consequent decline, and even extirpation, of many native aquatic vertebrates.

Park Setting and Key Resources

Size: 216 hectaresElevation range: 2,027–2,079 meters

Biogeography and physiography

Gila Cliff Dwellings National Monument lies in the Arizona–New Mexico Mountains ecoregion near the confluence of three major ecoregions in the American Southwest. This continental position—a transition between the Sonoran and Chihuahuan deserts on the east and west, and the Rocky Mountains and Sierra Madre to the north and south—is reflected in the monument's biodiversity. The monument includes steep but relatively shallow canyons, as well as portions of the channels and associated floodplains of the middle and west forks of the Gila River. It is part of the temperate forest biome. Average annual precipitation is 19.8 inches (504 mm).

Local geology and soils

The monument lies within an ancient caldera that collapsed following an enormous volcanic eruption. The surrounding mesas are composed of rhyolite, andesite, basalt, and welded tuffs interbedded with Gila Conglomerate. The floodplains and channels are composed of shallow alluvium from local deposition of these same materials. The park has not had a comprehensive soil survey.

Climate and hydrology

The climate of Gila Cliff Dwellings National Monument is typical of the Arizona–New Mexico Mountains ecoregion: highly variable, bimodal precipitation with a considerable range in daily and seasonal air temperature, and relatively high potential evapotranspiration rates. Approximately half of annual precipitation falls during summer thunderstorms, where maximum air temperatures often exceed 86°F and lead to violent (and often localized) rainstorms. The bulk of the remaining annual precipitation falls in relatively gentle events of broad extent, occasionally as snow.

Weather and climate data for Gila Cliff Dwellings National Monument and all other Sonoran Desert Network parks can be found at The Climate Analyzer, an interactive website that allows users to create custom graphs and tables from historical and current weather-station data. A weather and climate inventory was created for the Sonoran Desert Network in 2007. A more recent brief shows the magnitude and direction of ongoing changes in climate at Gila Cliff Dwellings National Monument.

The middle and west forks of the Gila River drain about 1,037,843 acres. Stream flow is highly variable and tightly linked to upstream weather events. Flooding is common, particularly following rain-on-snow events, spring snowmelt peaks, and intense localized summer thunderstorms.

Human habitation of the landscape

Human use of the monument area apparently has occurred for at least the past 2,000 years. However, the park's iconic dwellings were probably only occupied for perhaps 50 years during the 13th century A.D.

Protohistoric and historic use appears to have been dominated by the Chiricahua Apache during the 17th to 19th centuries, indicating a key cultural link with Fort Bowie National Historic Site and Chiricahua National Monument. During the historic period, homesteading, ranching, and guest ranching became dominant land uses in the area.

In addition to the cliff dwellings, contemporary and historic visitors were attracted to the area's magnificent wilderness, perennial waters, hot springs, and mild climate. Today, recreation is the primary human use of the Gila Cliff Dwellings landscape, with guest ranches, vacation cabins, and campgrounds distributed along the few roads and developed areas within the Gila Wilderness.

Native to the central and eastern U.S., the American bullfrog was introduced to the western U.S. accidentally, during trout stockings, through the aquarium trade, and for sport and pest control. In the West, it competes with and preys on native species.

Photo by Russ Ottens; University of Georgia; Bugwood.org

Key Issues

Amphibians and other aquatic invertebrates

Perhaps the most dramatic and alarming natural resource issue at Gila Cliff Dwellings National Monument has been the rise of non-native aquatic species, such as American bullfrog (Lithobates catesbeiana), and crayfish (Orcontectes spp.)—and the consequent decline, and even extirpation, of many native aquatic vertebrates.

Field surveys conducted from 2001 to 2003 failed to locate four species of amphibians that were historically common in the park: Mexican spadefoot (Spea multiplicata), Woodhouse's toad (Anaxyrus woodhousii), red-spotted toad (Anaxyrus punctatus), and Chiricahua leopard frog (Lithobates chiricahuensis). Declines in native amphibian species have been widely observed throughout the American Southwest, and are also attributed to habitat alteration, extended drought, increased UV radiation, non-native fishes, and chytrid fungus.

Invasive exotic plants

Biological invasions into new regions have increased at unprecedented rates in the past few hundred years. In the American Southwest, historic and current land management activities, such as livestock grazing and fire suppression, are thought to have made arid lands more susceptible to invasion and subsequent loss of native species and decreased biodiversity. In general, the southwestern semi-desert grasslands, savannas, and riparian community types are at greatest risk of invasion, due to modified disturbance regimes involving fire and herbivory. A biological inventory for the park detected 37 non-native species, comprising 8.5% of the flora. To date, tamarisk has not been detected within the park.

A Day in the Field with the SODN Streams Crew

Travel to Gila Cliff Dwellings National Monument with volunteer Vincent Sementelli to learn how the Sonoran Desert Network measures the health of streams. Vince also chats with aquatic ecologist Evan Gwilliam about how he chose and prepared for a career with the National Park Service.

Vincent Sementelli: This is a podcast on behalf of the National Park Service Desert Research Learning Center. My name is Vincent Sementelli. I’m a Volunteer-in-Parks, and we’ll be diving into my experience with the Aquatic Ecology Physical Science crew, of the Sonoran Desert Network: 1 of 32 National Park Service inventory and monitoring networks nationwide. As a volunteer, I was able to help out these career scientists in my capacity as a layperson, and get some special insight into what exactly it is these rangers and scientists are usually up to. As it happens, a childhood spent playing outdoors, in woods and fields and streams, might lend itself to a scientific mindset. In short, we’ll explore the perspective that was given to me by this experience, and through my time spent volunteering for the national parks.{Musical interlude} VS: My first assignment in the field was at Gila Cliff Dwellings National Monument, in the wilderness of southwestern New Mexico. I was to assist the Aquatic Ecology Physical Science crew – or AEPS, as we’ll refer to them hereafter – with streams monitoring. Here in one of the driest parts of the country, the AEPS crew studies water. At Gila Cliff and other national parks, they’re creating a long-term record of how much water is flowing, whether the water is clean, and how healthy the system is overall. On the days we went out, our goal was to map stream habitats and collect aquatic insects, both of which help tell us about stream health. My job was to create a habitat map for part of the Gila River where it crosses the monument. To do that, I followed the river, using a fancy GPS and lots of measuring tape.{In the field} Laura Palacios: So… VS: I’ll be filling in today as a professional cartographer for the NPS. LP: [Laughs]{Narration} VS: I was sort of kidding, but I was actually worried. This was a new experience for me. But the rest of my team was confident that I could figure it out.{Field} LP: [Laughing] So, what eventually is going to show up is you’re going to have eleven transects and we’re going to walk from one end to the other. And you map the entire way. We’re going to estimate the amount of each different habitat type. So there’s things like riffles, runs, pools, and glides: those are the four that we’re gonna experience. And we’ll go over that when we’re down there. VS: Okay.{Narration} VS: This was all new to me. As such, my volunteering for the AEPS team was very much like exclusive access to a skilled workshop, or rather, like a lab for a science class. A field trip. I had these professional ecologists teaching me all sorts of things – mostly just information that I’d need to better perform my side of things, but still, learning in this way is unlike anything else. Studying up, listening to a lecture – those aren’t the same as going out into the field with an expert and really doing the work with them.{Field}VS: I’m here at the Gila Trailhead Museum with biotechnicians Taylor Hubbard and Laura Palacios, uh, we’re gonna be doing some hydrology. Well, I’m not, I’m just gonna watch, and like maybe help carry stuff and measure some things… I guess maybe I’m gonna be a hydrologist too today, it’s gonna be fun. LP: [Laughing]{Narration} And from there, we searched for our sampling sites. We measured the rate of flow and the size of the particles (things like, sand, pebbles, boulders), assessing what sort of ecosystem they’d be classed as – which would influence what sort of critters we’d find – and we certainly found them. Mayfly larva, damselflies, toe biters, and many other strange insects I’d never really seen before. These were captured and bottled in preparation to send off to a lab, to more accurately determine their species and to get a good idea of what populations inhabited those ecosystems. Finding pollution-sensitive organisms, like those mayflies, is a good sign. They wouldn’t be able to thrive in a habitat with significant contamination, so they were precisely what we were hoping to find. {Field} [Rushing water] VS: So, uh, what exactly was I just doing here, Laura? LP: So you were doing the riffle sample. We divided it into nine sections and we took minute long samples in three of them. And we’re gonna see what the diversity of the bugs is in this little riffle. VS: So I was standing in the, uh, in the riffle here, catching bugs with this net, and uh, well also it looks like leaves and pebbles and… you mentioned something about pebbles, so actually, what are we going to do with the pebbles? LP: So the pebble count is used to classify the substrate, or the bottom of the stream, and we’re looking at the different size classes of what’s on the bottom. VS: Does that tend to like, uh, maybe influence what species of bugs might be living there? LP: Yeah, yeah, so each different size is gonna give different little kind of microhabitats or different areas for bugs to find food. {Narration} VS: And that was our first day. Before we went to sleep, we refined some of our data. I redid the map, making it a little bit more to scale and readable. I also asked Laura what we’d be doing on Day Two. {Field} VS: Okay. LP: And so when we do the hour-long sample tomorrow, I’m gonna have one of you guys timing and one of you guys catching bugs, and it’s gonna be like one minute in this little like two-meter-by-two-meter riffle, and then… VS: Okay. LP: …Thirty seconds in the next one. And so today is just kind of our planning day. LP: And so we go back to the same ones every year, and so while you guys are doing your macro sample, I’ll be running – we call it habitat classification – things like substrate and the wetted extent, and it kind of gives us a judgment of what could be living there, so then we can compare it back to the macros that are living there. VS: All right. Why is the timing a factor? Just to make it more statistically relevant kind of, or…? LP: Yeah, it’s something to do with this particular type of stream. It’s a high-quality cold water stream. And so New Mexico says you have to sample in fall. VS: Okay. LP: So we get to swim in cold water. VS: Yes. [Laughing]{Narration}In helping these water scientists, I saw a side of the parks that I’d never seen before. {Musical Interlude} {Field} VS: So what are we doing now? LP: Uh, you guys are going to perform the hour-long sample. It’ll normally take around two hours to do. [Laughing] LP: So how this works is one person will time – we distributed the habitats yesterday. So one person will say, you know, you have two minutes in this riffle. The other person will sample the whole time. Um, person with the timer, make sure that you’re only timing when the net is in the water. Travel time doesn’t count. That’s why it takes a little bit longer. VS: Okay. LP: So what you’re going to do is, attempt to in each little habitat that we decided, try to get as broad of a sample as you can. Uh, most of the time the macroinvertebrates are going to be down in the rocks, down on the bottom, or within like this woody debris. They’re not gonna be just kinda hanging out in the middle of the water. So what you can do is stomp your feet and swish behind you. You can do that, you can lift up rocks and rub the rocks with your hands or with your feet.[Running water] LP: Um, along the side of the banks, especially with this, um, the vegetation that hanging down, you can take the net and actually kind of like jab at it. VS: Okay. LP: As long as you’re keeping in mind to move the net upstream while you do it. Otherwise you’re going to dump the sample – it happens pretty frequently, just try to keep it in mind. If you do end up dumping the sample, um, all you have to do is… VS: Start over? LP: Yes [Laughing], is start over. LP: So that’s why around every fifteen minutes, I want you guys to sieve and actually put at least the majority of the sample into the ethanol. {Narration} VS: We were placing our samples into ethanol. This killed the invertebrates, preventing them from eating each other and compromising the sample, and to preserve the sample for eventual shipment to a lab. {Field} VS: Okay. You said you wanted to sort of measure this over time to see how it changes from year to year, say. What’s the, uh, what’s the endgame with this research? Like, what are you kind of looking for? Is it, um, like habitat change due to climate change, or just how… just how these change from… these habitats change from season to season or year to year in general or…? LP: Yeah, so it’s the same index that we do every year, and we’re kind of using that to compare the years. Yeah, like we want to just repeat the same area and see what changes are happening over time, and this is going to get us some different macroinvertebrates, because you’re going to get the ones that are in the slower water, so there’s a possibility of getting more things like worms, or sometimes the damselflies will hang out in a little bit of the slower water, things like that, so it’s just to make sure that we’re getting an actual representative sample.LP: So the whole goal is just to establish a baseline of what we can expect from the parks. We want to know what is healthy, what is working, and if there’s anything of concern. And so as long as we come back quarterly and we know what should be here, we can tell managers when something shouldn’t be, and if there’s something going on that they need to worry about. VS: Okay. {Narration} VS: We’d almost completed the protocol. We had experienced the end of our second day. Almost done. Tomorrow we would measure the river’s flow. We’d also collect samples to send to a lab where they would be analyzed for chemicals, metals, and nutrients. Then we’d head home. And that isn’t to say we were ready to leave, or excited to go. Gila Cliff Dwellings National Monument is a really beautiful wilderness, the walls of the canyon all vividly colored, the leaves turning on the cottonwoods that flanked the river. It’s just that it’s really rugged and remote. Long-untouched wilds can feel almost alien sometimes. And so I can say a small part of me was a little eager to leave the cold headwaters and make my way back west. {Music} {Narration}VS: Upon returning, I got to interview Evan Gwilliam, an ecologist for the Sonoran Desert Network, who leads the AEPS team. I asked him why he decided to become a scientist for the National Park Service. {Int.}VS: Okay. Why are you personally doing this? Is this a job you just kind of fell into? Uh, is this something you went to school specifically for?EG: Yeah, I went to lots of school for this.VS: [Laughing]EG: So this all hinges back to when I was about eight, and I spent a lot of time in the swamps and streams near my house, where I was growing up.VS: So you were interested in water from the get-go?EG: I was, yes. You know, I spent a lot of time outside, I mean… you know, in the summertime, I would wake up at dawn, I would get on my bike and then ride out to meet my friends, and we’d just play in the woods all days. And then, you know, in my town there was a… there was this, uh, loud, like… alarm that would go off at six o’clock at night from the fire station, I don’t know, it was really weird, like, like a, I don’t know, an air raid signal.VS: [Laughing]EG: [Laughing] And so that’s when we knew we had to come home for dinner. So my parents wouldn’t see us the whole day. That must have been great for them, but…EG: So yeah, I spent a lot of time outside, and uh, and so that, you know, I figured when I was trying to choose a career – How can I get paid to do that? – and voila, here I am.VS: So this isn’t just some arbitrary, uh, career you’ve fallen into, I mean there’s a real purpose of… I mean you have a real vested interest in this, you’ve had an interest in this since before you were even in academia. And so, I mean, what do you get out of that just beyond personal interest, I mean there’s like a conservation effort here, preservation effort, right? So…EG: Well, yeah, sure. I think that, for me, it’s important to know that I’m doing… I’m involved in something greater than just myself, all right? And so I like to be… it’s important to me that I can go home and I can tell my kids that today I’ve done something to make the world a better place? Maybe just a little bit, barely even noticeable, but I’ve done something to make it a better place. And I think that’s an important lesson to tell them, at least.{Narration}VS: I asked Evan how the different parts of the monitoring we did at Gila Cliff Dwellings—pebble counts, insect collection, flow measurement—help him to understand what’s going on there.EG: . . . it’s called the Streams Protocol, and it’s comprised of six different modules. So this is where is encompasses both the aquatic ecology and the physical science. So it breaks down, uh, streams in the riparian areas associated with it into these six parts, which are: the water quantity, which is how much water is coming through this system – and that’s the main driver of these systems, so…VS: Is that why we were measuring flow?EG: That is, and that’s possibly one of the most important things to understand about the system. And then it goes to: the morphology of the system, so uh, where on the landscape, where is the stream running, what is the bed material, what is the material that it’s running through, uh, the size of the particles, things like that. Then it goes to: the vegetation that is in and around the stream, in the riparian and the aquatic part of the stream. ||Then we get to: the water quality part, of which you were doing quite a bit when you were… when you were working with us. And then we have a section on macroinvertebrates, which are the insects and other critters that live in the streams, um, they can tell you a lot about the status of the stream. And then finally: fish and other wildlife.VS: Okay.EG: So that includes fish and frogs and other stuff that lives around the river.VS: Now, so all of these modules together, the macroinvertebrates, the quantity and quality, and everything else, what is the expressed function of all of these modules together? What is the goal, what is it doing, what’s it meant to accomplish in our measuring of these systems?EG: Sure. So I work for a larger program in the National Park Service called the Inventory & Monitoring Program, and what that basically means is in a particular park, you want to know what’s there – which is the inventory part of it. And how that thing is changing over time – and that’s the monitoring part.{Narration}VS: So within these protocols, Sonoran Desert Network ecologists study what we call vital signs. And just like your blood pressure or your body temperature or your pulse, they measure certain sets of data so they can establish a baseline for the health of an ecosystem. For streams, these are things like the presence of macroinvertebrates, bacteria populations, pollutant metals, surface water quantity, and the actual morphology or shape of the channel itself. Prior to my volunteering, I’d had no idea this much went into monitoring and maintaining the health of the parks. {Interview}EG: So we’re looking at what’s there and how it’s changing over time in these natural or near-natural or modified settings, but not directly in response to a management action.VS: So what’s the significance of this for us?EG: Exactly. So what we’re doing is trying… providing the data, the information to the managers, to make sure that that place, those trees, that stream… is able to be protected, preserved, and transmitted into the future. Not, and… you can take that, like at Saguaro, it’s making sure that this part of the Sonoran Desert with the saguaros is kept in a fashion that can be experienced by Americans into the future, and you can extrapolate that into all different places in the parks. And I think that is… our Park Service is an example for parks throughout the world, similar groups throughout the world. But it’s not the same, again, in America, we have preserved the good and the bad, which is incredibly important. You know? So that’s one of the reasons why I do this job. One is it’s, you know, a lot of fun [laughing], but that’s, I mean, it’s important to me, and I like being a part of it.{Narration, Music}VS: This is Vincent Sementelli for the Desert Research Learning Center. I recorded the music you heard throughout the podcast. Thank you for listening.